1. Field of the Invention
The present invention relates to a disk drive, a disk control method, a data read/write method, a data assignment method and a disk storage medium used in a hard disk drive (HDD) or the like.
2. Description of Related Art
In a disk drive drive, if data cannot be read/written from/into a physical sector normally, this sector is recognized as a defective sector and registered in a defect map. For example, a disk drive unit having a capacity of 2 GB is provided with a memory which contains a storage region corresponding to 2000 defective sectors in the form of a defect map.
Defective sectors are detected during manufacture or during a low level formatting of a magnetic disk. During a logical formatting, logical block addresses (LBAs) are allocated to physical sectors which are not registered in the defect map. The LBAs are used in communications with the host. The commands from the host will specify a sector by an LBA. Each disk drive has means to map LBAs to actual physical sectors essentially without regard to the LBA. Among other things this allows defective sectors to be in effect mapped out of use by not being assigned an LBA. The physical location of the sector is unknown to the host. Another consequence of LBA mapping is that sector 1 on one drive design might be mapped to a physical sector in a track near the center of the data area while in another drive sector 1 might be mapped to a track near the edge of the data area. In regard to defective sectors which are produced during the use of the disk drive unit, since LBAs have already been respectively allocated to these defective sectors by the logical formatting, these defective sectors are registered in the defect map and these LBAs are respectively allocated to substitutive sectors.
In general, a magnetic disk has a plurality of concentric, circular data tracks. Reading/writing from/into the magnetic disk is executed subsequent to a seek, namely, rotating the magnetic disk and moving a magnetic head substantially radially over the magnetic disk to position it at a particular data track.
The positioning of the magnetic head at the particular data track is performed by reading head position identification information and a servo burst pattern which are previously recorded on the magnetic disk.
FIG. 5 and FIG. 6 are diagrams illustrating track formats used in conventional hard disk drive units. FIG. 5 shows a track change on a single surface of the magnetic disk while FIG. 6 shows a cylinder change as a track change on a plurality of surfaces (or multiple surfaces) of the stack of magnetic disks.
Further, FIG. 5 shows concentric and circular data tracks n, n+1, n+2, . . . formed on the magnetic disk, and illustrates the track change occurring when the data recorded on the track n+1 follows the data recorded on the track n.
Furthermore, FIG. 6 shows concentric and circular data tracks n, n+1, . . . formed on each of disk surfaces, and illustrates the head change and the cylinder change as the track change occurring when the data recorded on the track n of the surface 2 follows the data recorded on the track n of the surface 1 and when the data recorded on the track n+1 of the surface 1 follows the data recorded on the track n of the surface 2. Data access by the head change is performed electrically without the seek, and hence the head change is performed more quickly. FIG. 6 also shows a case that the head change from the surface 1 to the surface 2 takes place first and is then followed by the cylinder change.
As has been described above, in any of the track changes on the single surface or the multiple surfaces, when the sequential data is accessed in sequence, a series of one-track seeks may take place in succession.
A disk drive according to the present invention includes a disk storage medium having concentric and circular tracks; and seek control means for controlling a seek in which a magnetic head is brought radially over the disk storage medium to be positioned on one of the tracks. The seek control means controls the seek in such a way that, when reading/writing sequential data from/into two of the tracks by radially moving the magnetic head, a distance between the two of the tracks is equal to or greater than twice as long as a track interval, i.e., moving to a track other than an adjacent track. The seek control means preferably assigns LBAs so that where a sequence of LBAs spans two tracks, the two tracks are not adjacent tracks.
A disk control method according to the present invention is the method for controlling a seek in which a magnetic head is brought radially over a disk storage medium having concentric and circular tracks to be positioned on one of the tracks. The method includes the steps of detecting an event at which a track change takes place; and controlling the seek in such a way that, when the track change between two of the tracks takes place, a distance between the two of the tracks is equal to or greater than twice as long as a track interval.
In the above-mentioned detecting step, a judgement may be made whether or not the sequential data is read/written from/into the last data sector among data sectors within the track. Further, a judgement may be made whether or not the sequential data is read/written from/into an innermost track or an outermost track.
In the above-mentioned seek controlling step, the seek maybe controlled so as to seek every other track from/into which the sequential data is read/written. Further, the seek may be controlled so as to initially seek in sequence even-numbered tracks on the disk storage medium, and subsequently seek in sequence odd-numbered tracks on the disk storage medium. Furthermore, the seek is controlled so as to initially seek in sequence odd-numbered tracks on the disk storage medium, and subsequently seek in sequence even-numbered tracks on the disk storage medium.
A data read/write method according to the present invention is the method for reading/writing sequential data from/into sectors of concentric and circular tracks on a disk storage medium. The method includes the step of reading/writing the sequential data from/into two of the tracks by radially moving the magnetic head in such a way that a distance between the two of the tracks is equal to or greater than twice as long as a track interval.
A data assignment method according to the present invention is the method for assigning sequential data to sectors of concentric and circular tracks on a disk storage medium. The method includes the steps of assigning, at first, sequential data to sectors on a first track; and assigning, then, sequential data to sectors on a second track, at least one track being disposed between the first track and the second track, if the sectors of the first track are full.
A disk storage medium according to the present invention includes a plurality of tracks, each of which has a plurality of sequential logical address blocks. The plurality of tracks includes a first track having a first sequential logical address block; a second track having a second sequential logical address block which follows the first sequential logical address block; and at least one track disposed between the first track and the second track. Thus, a disk storage medium according to the present invention includes tracks each having n logical block addresses (LBAs), where n is an arbitrary positive integer. The tracks includes a first track having k-th through (k+n-1)-th logical block addresses, where k is an arbitrary positive integer; a second track having (k+n)-th through (k+2n-1)-th logical block addresses; and at least one track disposed between the first track and the second track.
It is an object of the present invention to provide a disk drive, a disk control method, a data read/write method, a data assignment method and a disk storage medium which prevent a non-linear movement of the magnetic head and an increase of friction of the bearing even if the track width becomes narrower in order to increase the capacity, thus enabling an improved accuracy of positioning by the servo operation.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description below.